It's hard to think of a more significant influence on the small jazz ensembles of the last four decadesthan Miles Davis's second quintet, formed in the mid 60s. Davis was reacting to John Coltrane and Ornette Coleman's pioneering work and absorbing their structure-loosening innovations into his own music – just as he had done on at least three occasions since he first fought his way into Charlie Parker's 1945 group by a mixture of guile, persistance and raw talent. Back then, the young Davis had changed bebop's nervous sound with softer tones and spacious solos – a development that informed the Birth of the Cool sessions, with more languorous bop lines folded into sumptuous ensemble harmonies. Then came Davis's rejection of established jazz chords with 1959's Kind of Blue, as well as collaborations with big-band composer/arranger Gil Evans that produced jazz concertos such as Porgy and Bess and Sketches of Spain.

But by the 60s, jazz was being shaken up by the fearless (some might say foolhardy, or even unlistenable) challenges of musicians such as Coltrane, Coleman and pianist Cecil Taylor. The exploratory artist in Davis drew him toward these liberating possibilities, but he needed the attention of a broader audience. His reaction to free jazz was to reinvent his quintet with untried talents to see what would happen. Davis hired 16-year-old drum prodigy Tony Williams, fast-rising pianist Herbie Hancock (whose jazz-improv and pop instincts appealed to Davis), plus the Coltrane-esque Wayne Shorter on sax and bass powerhouse Ron Carter.

The band quickly became Davis's finest group. Their solos were fresh and original, and their individual styles fused with a spontaneous fluency that was simply astonishing. The quintet's method came to be dubbed "time, no changes" because of their emphasis on strong rhythmic grooves without the dictatorial patterns of song-form chords. At times they veered close to free-improvisation, but the pieces were as thrilling and hypnotically sensuous as anything the band's open-minded leader had recorded before.

Davis employed such unruly young sidemen not to flatter his remarkable trumpet sound, but to challenge it. I interviewed Hancock for the Guardian some years ago, and he described Davis's demand that his talented new partners, respectfully nervous of their boss's legendary ego at first, should turn up the heat on him. "Tony and I had got into the habit of playing all kinds of mixed rhythms ... so we started playing some of those rhythm things behind Miles too, things that were hard to predict, would sometimes swing and sometimes float. The first night we did it he stopped a lot in his solos, jerked around as if he was uncomfortable, not sure what to do, trying to find his way. Next day, he was more at ease, playing longer phrases, but still not into it. Then by the last set on the next day, he wasn't struggling with it any more at all. In fact he played so many unexpected things himself that it was me that was jerking around! In less than 24 hours Miles had not just grabbed the ball, but run beyond us with it."

The "second great quintet" first indicated the bridges it would build between Davis's post Kind of Blue work and his subsequent enigmatic music on 1964's Miles in Berlin, made after Shorter joined. Then came the remarkable sequence of albums such as ESP, The Sorcerer, Nefertiti, Miles in the Sky (hinting at the beginnings of jazz rock, with Hancock introducing the Fender Rhodes), Filles de Kilimanjaro and the stunning Live At the Plugged Nickel – but that's another story.